Micromechanical modeling approach to single track deformation, phase transformation and residual stress evolution during selective laser melting using crystal plasticity

Abstract

Single track scanning is a widely used method to evaluate the effects of rapid solidification of metals and to analyze their printability. Microstructure level stresses play a dominant role in causing material failure during deposition or poor performance on the finished product. This work formulates a thermomechanical crystal plasticity model capable of presenting microscale level evolution and residual state of stresses and strains in a single track event of selective laser melting. The present novel thermomechanical model is a vital piece of an overall workflow to analyze material properties and more complex performance inherent and dependent on the microstructure scale phenomena. The results show effectiveness of the model in addressing microscale residual stress heterogeneities dependent on the melt pool area thermal and microstructural evolution, including micromechanical phase transformations, and their interaction with the surrounding matrix on the studied H13 tool steel. The method is found exceptionally robust in terms of predicting microstructural residual stresses and deformation, while its greatest limiting feature is the requirement of prior solidified microstructure as an input for the computations.